Application of the Malaria Management Model to the Analysis of Costs and Benefits of DDT versus Non-DDT Malaria Control

Abstract

Introduction: DDT is considered to be the most cost-effective insecticide for combating malaria. However, it is also the mostenvironmentally persistent and can pose risks to human health when sprayed indoors. Therefore, the use of DDT for vectorcontrol remains controversial.Methods: In this paper we develop a computer-based simulation model to assess some of the costs and benefits of thecontinued use of DDT for Indoor Residual Spraying (IRS) versus its rapid phase out. We apply the prototype model to theaggregated sub Saharan African region. For putting the question about the continued use of DDT for IRS versus its rapidphase out into perspective we calculate the same costs and benefits for alternative combinations of integrated vectormanagement interventions.Results: Our simulation results confirm that the current mix of integrated vector management interventions with DDT as themain insecticide is cheaper than the same mix with alternative insecticides when only direct costs are considered. However,combinations with a stronger focus on insecticide-treated bed nets and environmental management show higher levels ofcost-effectiveness than interventions with a focus on IRS. Thus, this focus would also allow phasing out DDT in a costeffectivemanner. Although a rapid phase out of DDT for IRS is the most expensive of the tested intervention combinationsit can have important economic benefits in addition to health and environmental impacts that are difficult to assess inmonetary terms. Those economic benefits captured by the model include the avoided risk of losses in agricultural exports.Conclusions: The prototype simulation model illustrates how a computer-based scenario analysis tool can inform debateson malaria control policies in general and on the continued use of DDT for IRS versus its rapid phase out in specific.Simulation models create systematic mechanisms for analyzing alternative interventions and making informed trade offs.